NGUI 2.7 clipping with the new UI?

As you may know, the new Unity UI system(wich was released in 4.6) hits performance pretty hard. In my mobile app I have a ScrollView with multiple ScrollViews inside. Both of them have Mask components. I discovered, that the Mask component hits performance so hard, that I detect huge FPS drops on weak and even average devices. For example, iPhone 4 FPS drops down to 4-5 FPS, which is completely unacceptable. I want to find a way to replace the new UI Mask component with something else. Can I use the free NGUI 2.7 for this purposes? If yes, can someone give me some tips? If no, is there any other way? Except writing my own shader, I can't do that.